Protein requirement of baby pigs

Our earlier work with low-fat diets (Manners & McCrea, 1962) had shown no advantage in giving more than 25% crude protein to piglets over the period from 2 to 28 days of life.Our aims in the experiments now described were to determine if the requirement for protein is greater when high-fat diets are used, to compare fat and carbohydrate as energy sources, and to test the effect of homogenization on the utilization of dietary fat.The three experiments are numbered consecutively to those reported in the previous paper (Manners & McCrea, 1962).In the first (Expt 4) a control low-fat diet was compared with three diets containing different quantities of protein and in which 9 % lard replaced some of the maize starch in order to determine the effect of fat on protein requirements; in the second (Expt s) diets containing 21 % fat derived from dried whole milk and different quantities of protein were compared; in the third (Expt 6) the effect of a diet containing 20% lard that had been melted before incorporation was compared with the effect of a diet containing the same amount of emulsified lard.A third diet in which an equicalorific amount of glucose replaced the lard was included in the comparison in Expt 6. EXPERIMENTAL Experimental designA randomized block design was used.Four treatments were replicated eight times in Expt 4 and six times in Expt 5 , and three treatments were replicated six times in Expt 6.The significance of differences between treatments was tested by analysis of variance. Animals Large Whitex Wessex piglets were used in Expts 4 and 5.In Expt 6 two blocks of pure-bred Wessex, two blocks of Large White x Wessex and two blocks of Large White x Landrace piglets were used.